1. Field of the Invention
The present invention relates to a liquid crystal display device, and more particularly, to a dual display mode liquid crystal display device, a communication device using a dual display mode liquid crystal display device, and a method of fabricating a liquid crystal display device.
2. Discussion of the Related Art
In general, liquid crystal display (LCD) devices are commonly used in notebook computers and desktop monitors because of their superior resolution, color image display, and image display quality. The LCD devices have first and second substrates that are spaced apart and face each other, wherein an electrode is formed on the opposing interior surfaces of the first and second substrates, and a liquid crystal layer interposed between the first and second substrates. In addition, polarizers are disposed on exterior surfaces of the first and second substrates. Accordingly, when a voltage is supplied to the electrodes of the first and second substrates, alignment of liquid crystal molecules of the liquid crystal layer is changed in order to display images. However, since the LCD devices cannot emit light, an additional light source is necessary in order to display the images. Thus, a backlight device is position behind one of the first and second substrates to irradiate light to the liquid crystal layer, wherein the alignment of the liquid crystal molecules controls the amount of the light that is transmitted through the liquid crystal layer to display the images.
FIGS. 1A and 1B are schematic cross sectional views of a twisted nematic (TN) mode liquid crystal display device according to the related art, wherein FIG. 1A shows progress of light in an OFF state and FIG. 1B shows progress of light in an ON state.
In FIGS. 1A and 1B, first and second substrates 10 and 30 are spaced apart from and face each other, and first and second transparent electrodes 12 and 32 are formed on inner surfaces of the first and second substrates 10 and 30, respectively. In addition, a liquid crystal layer 40 is interposed between the first and second transparent electrodes 12 and 32, first and second polarizers 14 and 34 are disposed on outer surfaces of the first and second substrates 10 and 30, respectively, and a backlight 50 is disposed on a rear surface of the first polarizer 14. The liquid crystal layer 40 operated in a twisted nematic (TN) mode, wherein molecules of the liquid crystal layer 40 are arranged parallel to the inner surfaces of the first and second substrates 10 and 30. Accordingly, as shown in FIG. 1A, the molecules are twisted at right angles between the first and second substrates 10 and 30 when a voltage is not supplied to the first and second transparent electrodes 12 and 32. Conversely, as shown in FIG. 1B, the molecules are arranged perpendicular to the inner surfaces of the first and second substrates 10 and 30 when the voltage is supplied to the first and second transparent electrodes 12 and 32.
In FIGS. 1A and 1B, light transmission axes of the first and second polarizers 14 and 34 cross each other at right angles. In the OFF state, as shown in FIG. 1A, light produced by the backlight devices 50 passes through the first polarizer 14 and is transformed into first linearly polarized light and transmitted through the first substrate 10. Then, the first linearly polarized light is converted into second linearly polarized light while passing the liquid crystal layer 40 due to the right angle twisted of the molecules of the liquid crystal layer 40. Accordingly, the second linearly polarized light is parallel to the light transmission axis of the second polarizer 34. Next, the second linearly polarized light passes through the second polarizer 34 to display a full white image.
In ON state, as shown in FIG. 1B, the light produced by the backlight 50 passes through the first polarizer 14 and is transformed into first linearly polarized light and transmitted through the first substrate 10. Then, the first linearly polarized light passes through the liquid crystal layer 40, wherein the molecules of the liquid crystal layer 40 are arranged perpendicular to the inner surfaces of the first and second substrates 10 and 30, without being further linearly transformed. Since the first linearly polarized light is perpendicular to the light transmission axis of the second polarizer 34, the first linearly polarized light is blocked by the second polarizer 34, thereby displaying a full black image.
According to the related art, the backlight device is used as a light source, and images are displayed only along a single direction.